Guest Post by Willis Eschenbach
OK, folks, for everyone who wanted to put forth your favorite theory about how downwelling radiation from the atmosphere is a fantasy, or how a cool atmosphere can’t leave the surface warmer than no atmosphere, or how pyrgeometers are fatally imprecise … this is the thread for you.
However, I’m going to ask that before you start, you understand my actual position on these questions. So I strongly request that before you comment, you read the following four posts. That way, you’ll be clear about my thoughts on the matter.
Can A Cold Object Warm A Hot Object? 2017-11-24
Short answer? Of course not, that would violate the Second Law of Thermodynamics —BUT it can leave the hot object warmer than it would be if the cold object weren’t there. Let me explain why this is so. Let me start by introducing the ideas of individual flows and ne…
Radiating the Ocean 2011-08-15
Once again, the crazy idea that downwelling longwave radiation (DLR, also called infra-red or IR, or “greenhouse radiation”) can’t heat the ocean has raised its ugly head on one of my threads. Figure 1. The question in question. There are lots of good arguments against the AGW consensus, but this…
The Steel Greenhouse 2009-11-17
There is a lot of misinformation floating around the web about the greenhouse effect works. It is variously described as a “blanket” that keeps the Earth warm, or a “mirror” that reflects part of the heat back to Earth, or “a pane of glass” that somehow keeps energy from escaping. It is none of these things.
People Living in Glass Planets 2010-11-27
Dr. Judith Curry notes in a posting at her excellent blog Climate Etc. that there are folks out there that claim the poorly named planetary “greenhouse effect” doesn’t exist. And she is right, some folks do think that. I took a shot at explaining that the “greenhouse effect” is a…
OK, now that y’all have read those four posts, and you are all clear about my position, let me offer some data to focus the discussion. Figure 1 shows the month-by-month surface shortwave (solar, “SW”) and longwave (thermal infrared, “LW”) radiant energy flows at the SURFRAD station in Goodwin Creek, Mississippi. The US maintains something called the SURFRAD (Surface Radiation Budget) Network of eight surface measuring stations. These have a variety of sensors that, as the name suggests, measure a variety of surface radiation flows. Each station has a Downwelling Pyranometer, Upwelling Pyranometer, Downwelling Pyrgeometer, Upwelling Pyrgeometer, UVB Sensor, Photosynthetically Active Radiometer, Normal Incidence Pyrheliometer, and a Shaded Pyranometer. These are calibrated annually to assure accurate measurements. They collect data on an almost continuous basis, 24/7/365. The stations have data from 1995 to the present.
So I picked a SURFRAD station at random, Goodwin Creek, Mississippi. And I picked a year at random, 2014, and downloaded the monthly average data from here. After I plotted it up I thought “I wonder how well this agrees with the CERES satellite-based dataset?” So I added the corresponding CERES data to the chart. Here is the result.
Figure 1. SURFRAD and CERES data, Goodwin Creek, Mississippi. The CERES data is for the 1° latitude by 1° longitude gridcell where the SURFRAD station is located. The background shows the Goodwin Creek SURFRAD station.
Now, folks have been questioning lately whether the CERES data is accurate enough for the type of analyses that I do, whether it is fit for the purpose … this should allay some of their concerns.
With all that as prologue, here’s the important part of this discussion.
The red|orange lines show the amount of solar energy that is absorbed by the surface. It’s the net of the downwelling solar minus the solar that is reflected back upwards from the ground. As you can see, the annual average solar energy absorbed by the surface is about 150 watts per square metre (W/m2).
The yellow|gold lines, on the other hand, show the upwelling longwave (thermal infrared) energy, energy that is radiated upwards from the surface. The annual average upwelling longwave energy is about 395 W/m2.
Now, for all of you that think that downwelling radiation from the atmosphere is a mirage, here’s the question.
If on an ongoing basis the surface is only absorbing 150 W/m2 of solar energy and is radiating 395 W/m2 of energy … why isn’t it frozen solid?
Seriously. If it is constantly radiating far more energy than it is absorbing … why isn’t it a block of ice?
To me, the obvious answer is, the surface is also absorbing downwelling radiation from the atmosphere. In Figure 1 above, the blue|cyan lines show the total of the net solar (SW, red|orange lines), plus the downwelling longwave thermal infrared (LW) from the atmosphere.
The annual average of the net downwelling radiation at the surface (SW +LW), the total energy absorbed by the surface, is about 490 W/m2. This is about a hundred W/m2 more than the energy that is lost to radiation, with the rest of the surface energy loss being in the form of the net of the sensible and latent heat lost gained and lost by the atmosphere via convection and conduction.
So there you have it. If you don’t think that downwelling LW radiation leaves the earth warmer than it would be if there was no atmosphere, you need to explain the mystery source of the additional energy necessary to keep the earth from freezing. And no, it’s not geothermal heat. We know from borehole measurements that geothermal heat, in general, is on the order of a tenth of a W/m2 or so … and we’re missing about 395 W/m2 emitted minus 150 W/m2 absorbed equals 245 W/m2 necessary to prevent freezing.
So what is the mystery source?
Let me add that the most excellent agreement between the SURFRAD and the CERES data means that it’s not instrumental error, or scientists who don’t know what they are measuring.
So where is the energy coming from?
My best to all, let the bunfight begin, and please, keep it civil … I may be wrong, but I’m not an idiot …
As Usual I Politely But Loudly Request: QUOTE THE EXACT WORDS YOU ARE DISCUSSING. I can defend my own words. I can’t defend your interpretation of my words.